Driving device of the turn-table of a speaking machine



Apnl 18, 1961 L. THEVENAZ 2,980,429

DRIVING DEVICE OF THE TURNTABLE OF A SPEAKING MACHINE Filed March 24, 1958 IIIIII/IIIIII/II/I/ '/////////////////17//////1Zfi77///////l///I////l/l//.

United States DRIVING DEVICE OF THE TURN-TABLE OF A SPEAKING MACHINE Louis Thvenaz, Les Rasses, Switzerland, assignor to Thorens S.A., Sainte-Croix, Vaud, Switzerland, a cor- Duration of Switzerland Filed Mar. 24, 1958, Ser. No. 723,366 Claims priority, application Switzerland Apr. 3, 1957 i 6 Claims. (Cl. 274-39) In Order to obtain a musical reproduction of a high quality from a musical recording on record, it is necessary that the fluctuations of the rotation speed of the record about its average speed do not exceed 1 to 2% of this Furthermore, in order to obtain a very weak back ground noise level during the reproducing of a record, it matters to reduce in all the possible measure the transmission of vibrations to the pick-up device and to the record itself. To this aim, one seeks to mechanically isolate the motor with respect to the machine frame by" means of deadening devices. These devices are the more eflicient the more the motor is light with respect to the whole machine.

The vibrations of the motor of electrical or mechanical origin are, on the other hand, the more difiicult to master the more powerful this motor is. For these various reasons, one aims at giving the preference to a motor of a low power having a light weight and driving a turn-table of great inertia.

In order to obtain nevertheless an extremely rapid stabilisation of the record speed to its nominal value at starting time, a characteristic which allows the laying of the very sensitive pick-up onto the motionless record without appearing of disagreeable tune variations at the beginning of the hearing, some manufacturers have pro-;

posed to provide a turn-table driving device comprising a coupling located between the turn-table and the record to tent 2,980,429 I Patented Apr. l8, 1961 To remedy to this drawback, one has recommended a coupling which, in the disengaged position, suppresses be driven. Thus, the motor and the turn-table ofgreat inertia can be maintained in permanent rotation, where-,

by solely the mechanical connection between said turntable and said record being interrupted or re-establish at will. The devices of this type known up to now, are provided with various coupling devices. The most used one comprises an auxiliary washer pivoted on the turn-table shaft and resting on said shaft by means of felt strips. The record to be played is laid onto the upper face of this washer coatedwith'felt or rubber. For stopping the record, it is sufficient to hold back the washer ually or by means of a peripherical brake.

Still the experience shows that, despite the very small weight of such a washer and of the record laying on said Washer, the frictions between the turn-table and said washer, when'said washer is stopped, are sufficient to slacken the speed of the turn-table of great inertia down to such a value that a further rapid starting becomes impossible. One must then provide a muchmore powerful motor with the above mentioned disadvantages.

the greater part of the frictions between the auxiliary washer and the turn-table of a great inertia.

If it is not desired to foresee intricated devices already. known, one is brought to cause an axial displacement, either of the auxiliary washer or of the turn-table, in

order to bring them from an engaged position to a dis-' engaged one. Thus, it has been recommended to control the axial displacements of the auxiliary washer by means of a rod coaxial with the turn-table revolving axis and going through a hollow shaft carrying said turn-table.

Now, in addition to the manufacturing difiiculties, such hollow shafts do not allow to make use of the only thrust hearing which has the best performances and is fully satisfying for carrying a turn-table of great inertia: an only ball resting on the end of the shaft rotating on a plate made out of a special material such as nylon. The ball bearings and peripheric smooth thust bearings do not enable to realize, by mass production, a bearing quality which would satisfy the very high requirements for high quality speaking machines, thefrictions between the turntable and the fly-wheel, the speed of this fly-wheel do not undergo, at the stopping of the turn-table, such a speed reduction, as to cancel all the advantages sought by this vice of the turn-table. of a speaking machine, which com prises a coupling device connecting a fly-wheel to said turn-table and an actuating device of said turn-table causing an axial displacement of said turn-table along a centering member and the interruption of the mechanical connection connecting said fly-wheel to said turn-table. Said device distinguishes from the known devices by the fact that said actuating device comprises an actuating member pivoted with respect to the frame of the speaking machine and disposed between the upper face of said frame and the under front face of a peripherical flange of said turn-table.

The attached drawings Show schematically and by Way of example a form of execution of the coupling device according to the invention.

Fig. 1 is a partial cross section along line II of the Fig. 2.

Fig. 2 is a top view.

Fig. 3 is a partial cross section at a line IIIIII of the Fig. 2. v

Fig. 4 is a partial cross section at a greater scale of a detail.

In the attached drawings, only the members and parts of the talking machine necessary to the good understanding of the coupling device object of the present invention have been represented.

The frame 1 of the speaking machine bears a bearing 2 fixed by bolts 3 and within which rotates freely a shaft 4 onto which is fastened a fly-wheel 5 of a sufficient great inertia for the absorption of the speed variations due to mechanical or electrical causes. The shaft 4 bears by the intermediary of a thrust ball 6 on a plate 7 fastened to the bottom of the bearing 2, by screws 8. i

The fly-wheel 5, preferably made of cast iron, is fixed by bolts 9 on a collet 10 of the shaft 4.

In order to increase the inertia of the fiy-wheel 5, the greater part of its material is distributed along its periphery which has a circular flange 11, the internal cylindrical surface 12 of which is accurately machined. Said greater scale along cylindrical surface, accurately centred with respect to the shaft 4, is in frictional contact with a frictional driving member (not shown) as described and represented P EP f h i si ene a hiapeo an .0

V is :zthefollowingz; .r V

When the control member 3 6 is set in the position A,; r

A turn-table 13,: preferably inade of'a' light alloy such as aluminium, is driven in the rotation of the fly-wheel .5

by a friction coupling constituted, ;on the one hand, by

' feltstrips"14"glued on: the h fgfirh ehr the' hy vvh er s,

andg onithe othrhani'byl circular rib 15 16 carried by'the'shaft4 and pi'ese'nts'a;peripherical machine tinder voltage,

wheeli5. and extends by. some millimetres lower than'the under face." of said rim, The turn-table 13 has adished' centraLpart 191 engaged into acentralrhousing provided in the 'fly-wheel 5. A i'circular piece 2 1 having the general form ofwaeup'providedwith arim 22iis fastened byserews-ZE: inside; the-bottom ofithe dished p'artjl'Q.

.Betweehthe? rimfzz 1 of said circular piee121:;and th turniable 13 isjpinchedawasheii'24; madeiof rubber,

pho l phi ecor t o hown-)'..;: r l

In t the inside of; this cup 2: f1 mounted; a centering. -t u rn ed cup; ianieter O t id 'c n e i part zixprresp n ameter of the central bore of a i6 /z in',;-record prosyhthetie'material or of felt, provided-for Supporting the 16,011' the contrary,fcorresponds tothe diameter of ritral -horerof the various records;.-provided with a $51511 i central bore, A This? centering; part 125 submitted to: theaction of a spring 26,, s lides'along the pin 1 6- and is" able to 'occupyjthe two following positions ,(a), A withdrawn, position .in--v vhich its 1 upper -face 27 is lloo'ated inthe plane of the' s'urface gfi of thewasher 24'. This 'part}25,takes automatically saidwithdrawn position under the action of the weight ofafrecordto be played having a small ceritraLbore,- Iaidontothewasher 24;

i Araised 01' Working position: it projects. out, of the surface 28 7 An operatingmember 29 having l ha eb u a 9f Q r ecarri$ 7(4)" A 30 E l i .1 a hole provided in the 'frame; a

l pin 3 vided 'inthe frame, Springs 33 (Fig.3); bearing on theframe under faceand exerting'a push onto washers 34 carried by the pin 31 and the pivot 3 Q,.tend tornaintain 1 36 lpj n g g pmber 29 in its restppo sition (shownlon ol m er fifi nr tmdinal tw w respect to the turn-table; i f

(d) Three bores 37 located approximately at 90 one to another. 1 7 t r The frame 1 is provided with three gudgeons 39, each A of which having a countersink provided in its upper front face '40, located in the'pla'ne of the up'per face' ll ofthe frame. 7 A ball 42 is housed withineach of these countersinks; The working of machine the part 29 takes the position s'hown'infull liliesv in the Fig; 2. For this position, thebores 37 'providegl'in this part '29 correspond tofthe balls'ilz, so that under theactionj r Y t r r. a 60 onthe Fig. l, in which the balls 39 enter into thes'e bores of the springs 33, this part 2 9' takes"a restposition, shown 37, so that the under face of shid'part 29 cornes to laylonto the upper face 41 of the framel "Ihe turn-table '13 is then laying by the intermediary of the "circulatorjr'ih onto the felt strips 14, so that 'saidturfi -tablei's driven inrotapivots on the pivot 30, the pin l'il slides" in the guiding' port '32, and the balls 4 co-operating with the edge of thebores 37 provoke alifting movement ofthe part 29.

.v vi'th a large central bore. "1 'he diame ter of the:

passing through a guiding portelil pro- 1 chanical connection between the turn-table 13 and the fly wheel 5 is interrupted." This turn table stops although the fly-wheel continues to be driven in rotation. v a

For the hearing of a gramophone record, the operator 'put the record onto the washer 24, places the control member 36- in thejpositionh and put 'the 'motorof the The fly-wheel 5 is then driven 'inrotation while the record to be Played stay, motionlessL When said fly- ,wheel has'reached its nominal spe'ed and that this speed has stabilized, the operator pufthe pickup o'nto' 'the gramophone record to beplayei-which'is still motion- 1 less, then operates the control member3 6 up .to theposition A, in ofder to'i'setup a mechanical connection between the turn-table 13 and the flywheel 5 and thus the driving in rotation of the turn-table 13 and of the record to be, played.v The ma s stof the turn-table 13 androf the Yrevolution;at thenominal speed." 3

I he "described "coupling dezvi ce of hf ejrg simple conception and "ei'1ables,' when it is in the disengaged position,

a to suppress practically all fiictions between the driving part and the driveii'partl-f'Cdnseouently'theifly wheel 'toi'maintain the speed stabilit'y' of is dfly wheel' 5 running free; "1 fr? W r Furthermore, the turn-table 13? made of aluminium haststill an additional advantage thatarinotb'e neglected.

5. v Consequently,it. is not necessary to provide a flywheelmadezof .aluminium,'thefsizes of whichcould become very; large and 'the' cost price very high; if one desiresto; obtaina suflicient fly-wheel eifectmf T In the device according to the'invention, one may foresee a -fly-wheel' 5 made of cast iron, whichtlianks to its high material specific-weight, its machining easiness, its stahilityof;dimensionsgand its low cost price, presents great advantages with regard to a turn-table of aluminium worlging as fly-wheel; withoutistillfbeing"v prejudicial to the quality of the musical reproduction. 'The' playing surface of the record iseifectively sufficiently: distant from the ferromagnetic mass of the fly-wheel, 5;s o that the influence of this mass onto a magneticpick-upcan be entirelyheglected. 7

1Lastly, the periphericalsurface of the flange :17 can easily be polished, so es to give -a fine sight to the entire dgiving -device of the grarnophonerecord,

,A form Qi .pitheitum t b e.dr in rd object of: 'the invention, has beendescribedjhere and by why of. example and with reference to the attached drawings,vbut' it is clear that multiple variants can be fore seen. --Thus, for example, the balls 42 and the correspondingf bores provided fina the operating member 29 couldbeire'placed by an other operating means enabling to provoke fan; aiiial, displacement .of the operating member, atjthetimej offitsimanual operation in an angular displacementiround, its pivot '30. Such operating means operating one withanoth'er. r

During'its displacementjsaidjpart 22' 'comesf'intofc'ontact r with fthe u der :frontifaoe of the flange "17 and li sfthe turn-table" 1s; chhs'ehhehuy the circularfrih sle eves could; for example, be constitutedbywedges fastened to the frame and to ith'e'joperati g member and coa l 1. In a phonograph comprising aframee artllrntable having a depending peripheralf'flange a', motor, a 'flywheel driven rotatio'n by jsaid'mototj' a; centering member of said turntable andjafrictionf coupling connecting said turntable to said iflywheel', the: combination of ihnjaetuatingd Ce comprising j'a'nafciiate" actuating member'pivoted on s'aidYrame'efI said phonograph and displaceabie' fromX'EsfTKa Working position, said I actuating member being located between the upper surface of said frame and the lower front surface of said peripheral flange of said turntable, means carried by said actuating member, said actuating device comprising further means carried by said frame, said means carried by said frame engaging said means carried by said actuating member when said actuating member is in its rest position and abutting against the lower surface of said actuating member when it is located in its working position, whereby said turntable rests on said flywheel and is driven in rotation by said flywheel through said friction coupling when said actuating member is in rest position and on the upper surface of said actuating member when it is in its working position, disconnecting said turntable from said flywheel and maintaining said turntable in a fixed axial position.

2. A phonograph according to claim 1 and in which said means carried by said actuating member are constituted by openings made in said actuating member, and in which further said means carried by said frame comprises housings made in said frame and balls located in said housings.

3. A phonograph according to claim 1 and in which said friction coupling comprises a circular rib provided on the under surface of said turntable, and supple pieces having a high friction coefficient located on the upper surface of said flywheel, said turntable resting on said flywheel by the intermediary of said rib and said supple pieces.

4. In a phonograph comprising a frame, a flywheel of large inertia revolving in a bearing secured to said frame, a turntable of smaller inertia coaxially mounted on the upper surface of said flywheel, centering means in said flywheel for said turntable, friction coupling means on said flywheel for said turntable, the outer edge of said turntable having a depending peripheral flange larger than the edge of said flywheel, the combination of a plurality of lifting means angularly disposed under the outer edge of said turntable and mounted on said frame for reciprocal movement between a rest position in which they are out of contact with said outer edge of said tumtable and a lifted position in which they are engaging and lifting said turntable by its outer edge for disconnecting said turntable from said flywheel and maintaining it in a fixed axial position, and a manually-actuated control member mechanically connected to said lifting means to simultaneously move them between their rest and their lifted positions.

5. In a phonograph comprising a frame, a flywheel of large inertia revolving in bearing means in said frame, a turntable of smaller inerita coaxially mounted on the upper side of said flywheel, centering means in said flywheel for said turntable, friction coupling means on said flywheel for said turntable, the outer edge of said turntable having a depending peripheral flange larger than the edge of said flywheel, the combination of a manually-actuated control member pivoted on said frame for angular and axial movement about an axis substantially parallel to the axis of said flywheel, a plurality of lifting means on said control member angularly disposed under the outer edge of said turntable, cam means on said frame and on said control member adapted to transform an angular displacement of the control membar and an axial displacement of the same from a rest position in which said lifting means are out of contact with said outer edge of said turntable to a lifted position in which said lifting means are engaging and lifting said turntable by its outer edge for disconnecting said turntable from said flywheel and maintaining it in a fixed axial position.

6. In a phonograph comprising a frame, a flywheel of large inertia revolving in a bearing in said frame, a turntable of smaller inertia coaxially mounted on the upper side of said flywheel, centering means in said flywheel for said turntable, friction coupling means on said flywheel for said turntable, the outer edge of said turntable having a depending peripheral flange larger than the edge of said flywheel, the combination of a control member formed as a substantially semi-circular shaped lever and disposed in a substantially coaxial position, underneath and parallel to the outer edge of said turntable, said control member being pivoted for angular and axial movement on said frame about an axis parallel to the axis of said flywheel, manuallyactuated means on said control member for controlling the angular displacement of this latter, stop means in said frame determining two angular end positions of said control member, cam means in said frame and in said control member adapted to transform the angular displacement of the control member to an axial displacement of the same from a rest position in which said control member is out of contact with said outer edge of said turntable and a lifted position in which said control member is engaging and lifting said turntable by its outer edge for disconnecting said turntable from said flywheel and maintaining it in a fixed axial position.

References Cited in the file of this patent UNITED STATES PATENTS 2,278,680 Thompson Apr. 7, 1942 2,627,414 Sear Feb, 3, 1953 FOREIGN PATENTS 702,090 Great Britain Jan. 6, 1954 

